1. Field of the Invention
The present invention relates to an apparatus for transmitting connecting status, an apparatus for generating display data thereof and a method of displaying the same suitable for networks corresponding to the IEEE 1394 standard.
2. Related Art Statement
In recent years, IEEE (The Institute of Electrical and Electronics Engineers, Inc.) 1394 has prevailed as a unified standard for digital interface systems and as a low-cost peripheral interface suitable for multimedia use in order to transmit and receive data among digital image devices. IEEE 1394 enables multiplex transfer of a plurality of channels. IEEE 1394 has also become a digital interface suitable for image transmission because it has an isochronous transferring function which assures the transfer of image and voice data in a given period of time.
IEEE 1394 can form topologies in daisy-chain and tree shapes, and each bus is able to be connected with up to 63 nodes.
As IEEE 1394 allows such free connecting forms, it becomes convenient when a display of present connecting status is permitted. Present connecting status is designed to be managed by a bus manager provided in a predetermined single node in a bus.
However, not all nodes with functions of bus manager have displaying parts. Consequently, in order to display connecting status, connecting information from a bus manager should be transmitted to a node having a displaying part, but there is no standard for transmission formats to transmit connecting information.
It is possible, in this case, too, to display connecting status using a displaying part of another node by generating image data showing a display of connecting status from connecting information of a bus manager and transmitting these image data. In this case, however, the amount of data to transmit becomes enormous increasing burdens on both sides of a bus manager and a displaying part.
Meanwhile, data transfer protocol of IEEE 1394 is defined by three layers (hereinafter also defined as 1394 layers), a physical layer, a link layer and a transaction layer. Though these IEEE 1394 layers have been standardized, there is no common standard, for display layers which regulate management of hardware and provision of user interface at a node using operating system (hereinafter referred to as OS). Similarly, there is no common API (Application Programming Interface), which is a standardized interface for applications to use services such as OS.
Recently, in the fields of information equipment and home appliances, there has been a tendency to make these display layer and API common. However, API cannot be made common because standardization of data formats for connecting information from a bus manager has not been realized yet.
Another problem is that, in IEEE 1394, a maximum number of hierarchies (hop count) from a root is limited to 16 when connection is done in a tree-shape. When connecting status is not displayed in an easy way to secure the hop count, users might connect exceeding a maximum hop count permitted. Besides, when connection exceeded a maximum hop count, it is not simple to distinguish equipment which should be disconnected.
As stated above, there have been problems; that no standard exists for data to transmit connecting status displays from a bus manager having topology information to a display layer having displaying functions or from a node having a bus manager with topology information to a node which is a displaying equipment with no such function; and as a result, that it is impossible to display connecting status without increasing burdens on both of the outputting side of connecting information and the displaying side. Another problem is that it has been impossible to design display layers and API's as common devices. Another problem is that there has been no display of connecting status to allow the hop count to be secured easily.